I've only gotten to play one scenario so far (as the keeper). It was 1-1B. I thought it was pretty good for a first play. The investigators were new too, so they didn't really get why I took their samples and ran, and before they knew it, the Shoggoth was on his way out the door. Anyway, I am playing with another group this Thursday. All of them are new players too, and I am going to be the keeper again. Any suggestions as to which scenario and objective I should do? Keep in mind, they are new players, but I have some experience, so I can help them out a bit. Thanks guys.

So far, I think 1C has provided the most fun game as it really came down to the wire for the investigators and only escaped in the very final turn due to very well timed usage of all of their "once per game" advantages. Just the tenseness of that situation, snatching victory from the jaws of defeat (or at least, stalemate) made it a very memorable game. So far though, only really played all the variations of the first scenario.

If you prefer to throw in more type of monsters and have them around the table longer, I would suggest 2C or 2B.

If you want to go fro a more subtle Mythos card oriented scenario, increasing the tension through poltergesit effects and such, with very little monsters on the table, go for 4C.

Story 5 seems like a lot of fun but I would leave it for expereinced players (Have not played it yet myself)

I would not pick a "Kill x investigators" Objective story for a first run since you need to be quite aggresive on your players and that might discourage them a bit at the begining. But depends on your group, I guess.